There are a couple of ways to mask an alignment, using the AutoCAD mask,
that masks everything and uses draw order, or use an AEC Mask Block (part of
the under documented AEC Utilities that ship with Civil 3D). This tip uses
the AEC mask block because it allows a more selective mask, and we can
anchor the mask to the alignment.
Here are the steps...
1. Draw a closed polyline around the area to wipe out on the alignment
2. Use the command: ConvertLineworkToMaskBlock
a. Select the polyline you just made
b. Change the radio button in the dialog to "Select AEC Objects to Mask"
c. Select "Erase layout geometry"
d. Hit OK
e. Select the alignment. This should hide your alignment, but you'll may
still see the outline of the mask.
3. Change the layer of the new mask to the "Defpoints" layer or another no
plot layer.
ALTERNATIVE to the DEFPOINTS:
3. Select the Mask, right click and select "Edit Mask Definition..."
4. In the "Mask Block Definitions Properties" dialog,
a. change the tab to the "Display properties"
b. double click on the "General" line
c. Change the layer of the "Boundary Profile" display component to
something that won't plot. You could also turn it off, but then it becomes
very hard to select. I made a noplot layer and then changed its color to 251
(almost black).
d. hit OK a couple of times.
You should now be back in the drawing, and have a mask applied only to the
alignment.
EXTRA COOL:
1. Draw a long thin closed polyline (about the length that you want to mask)
along the x axis. This doesn't have to be along the alignments
2. Follow the steps above to convert the polyline to a mask block.
3. Use the "Anchor" command with the "CUrve" option.
a. Select the mask to anchor
b. Select the alignment to anchor to.
4. The mask will jump to the alignment and will be anchored to it. you can
slide the mask along the alignment using the grip. If the alignment moves,
the mask will move with it.
If you need to change the size of the mask, right click and choose "Edit
Profile in Place" (the profile is the outline of the mask).
Hope this helps!
Peter Funk
Civil 3D Product Manager